WorldCat Identities

Segoufin, Luc

Overview
Works: 12 works in 16 publications in 2 languages and 298 library holdings
Genres: Conference papers and proceedings 
Roles: Author, dgs, Other, Thesis advisor, Opponent
Publication Timeline
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Most widely held works by Luc Segoufin
Proceedings of the 13th International Conference on Database Theory by Luc Segoufin( )

2 editions published in 2010 in English and held by 235 WorldCat member libraries worldwide

Annotation
Conjunctive queries, arithmetic circuits and counting complexity by Stefan Mengel( )

1 edition published in 2013 in English and held by 29 WorldCat member libraries worldwide

This thesis deals with several subjects from counting complexity and arithmetic circuit complexity.The first part explores the complexity of counting solutions to conjunctive queries, which are a basic class of queries from database theory. We introduce a parameter, called the quantified star size of a query phi, which measures how the free variables are spread in phi. As usual in database theory, we associate a hypergraph to a query phi. We show that for classes of queries for which these associated hypergraphs have bounded generalized hypertree width, bounded quantified star size exactly characterizes the subclasses of queries for which counting the number of solutions is tractable. In the case of bounded arity, this allows us to fully characterize the classes of conjunctive queries for which counting the solutions is tractable. Finally, we also analyze the complexity of computing the quantified star size of a conjunctive query.In the second part we characterize different classes from arithmetic circuit complexity by different means, including conjunctive queries and constraint satisfaction problems, graph polynomials on bounded treewidth graphs, and an extension of the classical arithmetic branching program model by stack memory.In particular, this yields new characterizations of the arithmetic circuit class VP, a class that is central to the area but arguably not well understood.Finally, the third part studies the complexity of two questions on polynomials given by arithmetic circuits: testing whether a monomial is present and counting the number of its monomials. We show that these problems are complete for different levels of the counting hierarchy, which had few or no known natural complete problems before. ; eng
Database theory : ICDT 2010 : 13th International Conference on Database Theory, Lausanne, Switzerland, March 23-25, 2010 : proceedings by International Conference on Database Theory( )

1 edition published in 2010 in English and held by 18 WorldCat member libraries worldwide

Manipulation de données spaciales et topologiques by Luc Segoufin( Book )

3 editions published in 1999 in French and held by 5 WorldCat member libraries worldwide

LES OBJETS SPATIAUX, DE PAR LEUR COMPLEXITE, NE PEUVENT EN GENERAL PAS ETRE DECRITS DE FACON EXTENSIVE, MAIS SEULEMENT INTENSIONNELLEMENT, CE QUI POSE DE SERIEUX PROBLEMES AUX SYSTEMES DE GESTION DE BASES DE DONNEES. DE LA QUALITE DE LA MODELISATION DES DONNEES DEPEND LA FACILITE DE LEUR MANIPULATION ET L'EFFICACITE DES TECHNIQUES D'EVALUATION QUE L'ON PEUT METTRE EN UVRE. LA REPRESENTATION DES OBJETS A L'AIDE DE CONTRAINTES REND POSSIBLE UNE MODELISATION EN TERME D'ENSEMBLES QUI PERMET UNE MANIPULATION AU MOYEN D'OPERATIONS HABITUELLES COMME CELLES DE L'ALGEBRE RELATIONNELLE. L'EVALUATION DES REQUETES SUR LES OBJETS SPATIAUX A GENERALEMENT UNE COMPLEXITE EXPONENTIELLE EN LA DIMENSION DES DONNEES, CE QUI LIMITE LA PORTEE PRATIQUE DES SYSTEMES POUR DES DIMENSIONS ELEVEES. ON MONTRE COMMENT DANS LE CADRE DU MODELE CONTRAINTE, IL EST POSSIBLE D'UTILISER DES CRITERES TELLES QUE LA DIMENSION, LA GEOMETRIE ET LA TOPOLOGIE DES DONNEES POUR MAITRISER LE COUT D'EVALUATION DES REQUETES. POUR REDUIRE LA COMPLEXITE EN UNE FONCTION LINEAIRE EN LA DIMENSION, ON PROPOSE DES TECHNIQUES D'EVALUATION BASEES SUR DES APPROXIMATIONS. ON MONTRE AUSSI COMMENT RECONNAITRE DANS LA REQUETE DES BLOCS CORRESPONDANT A DES PROBLEMES CONNUS DE GEOMETRIE. UNE EVALUATION EFFICACE DE LA REQUETE EST ALORS OBTENUE EN REMPLACANT CES BLOCS PAR L'ALGORITHME CORRESPONDANT. ENFIN, ON MONTRE COMMENT REPONDRE PLUS RAPIDEMENT A DES REQUETES TOPOLOGIQUES A L'AIDE D'UNE STRUCTURE FINIE APPELEE GRAPHE TOPOLOGIQUE ET DES TECHNIQUES DE REECRITURE DE FORMULES. POUR FINIR, ON VALIDE CONCRETEMENT LA PORTEE PRATIQUE DE L'APPROCHE PAR CONTRAINTES ET DES CONCEPTS DEVELOPPES DANS CETTE THESE A L'AIDE D'UN PROTOTYPE, DEDALE, DONT ON PRESENTE LA CONCEPTION ET L'IMPLANTATION
On Invariant Formulae of First-Order Logic with Numerical Predicates by Frederik Harwath( )

1 edition published in 2018 in English and held by 4 WorldCat member libraries worldwide

Active Context-Free Games by Anca Muscholl( )

1 edition published in 2005 in English and held by 2 WorldCat member libraries worldwide

Analyse de XML avec données non-bornées by Claire David( Book )

2 editions published in 2009 in French and held by 2 WorldCat member libraries worldwide

The motivation of the work is the specification and static analysis of schema for XML documents paying special attention to data values. We consider words and trees whose positions are labeled both by a letter from a finite alphabet and a data value from an infinite domain. Our goal is to find formalisms which offer good trade-offs between expressibility, decidability and complexity (for the satisfiability problem). We first study an extension of first-order logic with a binary predicate representing data equality. We obtain interesting some interesting results when we consider the two variable fragment. This appraoch is elegant but the complexity results are not encouraging. We proposed another formalism based data patterns which can be desired, forbidden or any boolean combination thereof. We drw precisely the decidability frontier for various fragments on this model. the complexity results that we get, while still high, seems more amenable. In terms of expressivity theses two approaches are orthogonal, the two variable fragment of the extension of FO can expressed unary key and unary foreign key while the boolean combination of data pattern can express arbitrary key but can not express foreign key
13th International Conference on Database Theory 2010 (ICDT 2010) : ACM international conference proceedings series : Lausanne, Switzerland 23-25 March 2010 by International Conference on Database Theory( Book )

1 edition published in 2010 in English and held by 1 WorldCat member library worldwide

13th International Conference on Database Theory 2010 : (ICDT 2010) ; Lausanne, Switzerland, 23-25 March 2010 by International Conference on Database Theory( Book )

1 edition published in 2010 in English and held by 1 WorldCat member library worldwide

Query enumeration and nowhere dense graphs by Alexandre Vigny( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

Les travaux présentés dans ma thèse se situent à l'interface entre complexité, algorithmique et logique. Plus particulièrement, on s'intéresse à la complexité d'évaluation de requêtes.Plus précisément, étant donné G un graphe fini. Une requête q définit un sous ensemble de k-uplets de sommets de G que l'on note q(G). On appelle k l'arité de q et on se essaye alors d'effectuer efficacement les taches suivantes :1) décider si l'ensemble q(G) est vide ou non.2) décider si un k-uplet donné appartient à l'ensemble des solutions q(G).3) calculer le nombre de solutions.4) énumérer les éléments de q(G).En ce qui concerne la 4ème tache, un algorithme qui va énumérer les solutions sera décomposé en deux parties. La première est appelé le pré-calcul et sert à préparer l'énumération. Idéalement cette étape de requière qu'un temps linéaire en la taille du graphe. La deuxième étape est ensuite l'énumération des solutions. Le temps nécessaire pour obtenir une nouvelle solution est appelé le délai. Idéalement on souhaite que le délai de dépende pas de la taille du graphes mais uniquement de la taille de la requête. On parle alors d'énumération à délai constant après pré-calcul linéaire.Au début de cette thèse, une grand part des interrogations au sujet des classes de graphes pour lesquelles une énumération à délai constant serait possible semblait se trouver au niveau des classes de graphes nulle-part dense. Le résultat principal de cette thèse est de montrer qu'il est possible d'énumérer les solutions des requêtes du premier ordre sur les graphes nulle-part dense avec un délai constant après un pré-calcul pseudo linéaire
ICDT 2010 proceedings, March 23-25, 2010, Lausanne, Switzerland by International Conference on Database Theory( Book )

1 edition published in 2010 in English and held by 0 WorldCat member libraries worldwide

Manipulating Interpolated Data is Easier than You Thought (Research)( )

1 edition published in 2000 in Undetermined and held by 0 WorldCat member libraries worldwide

 
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Audience level: 0.49 (from 0.40 for Active Con ... to 1.00 for ICDT 2010 ...)

Languages
English (10)

French (5)